e23036 Background: Acute inpatient hospital care contributes substantially to variation in cancer care costs across the United States. The CMS Hospital Outpatient Quality Reporting Program’s OP-35 rule penalizes health systems for having higher-than-expected rates of emergency department (ED) visits or inpatient admissions for ten potentially preventable conditions within 30 days of receiving chemotherapy. To commence a systematic, automated, risk-adapted program to maximize safety outcomes, we identified independent risk factors specific to cancer patients in the Inova Health System (a 5-hospital, 5 million-patients hospital system in Virginia/greater metropolitan DC). Methods: We identified all cancer patients who received chemotherapy within the previous 30 days and presented to the ED or were admitted between 1/1/2018 to 12/31/2021 for one of the OP-35 toxicities as their primary or secondary diagnoses at the time of the acute care evaluation. Data included demographics, insurance coverage, cancer diagnosis, co-morbidities, and status (alive/dead) at last follow up. A zero-truncated Poisson regression analysis was performed in R v4.1.1. We further performed risk analysis within comorbid conditions by creating a matched cohort of patients by sex, age at first treatment, race, and cancer type who did not have an ED or admission visit due to OP-35 events during this same period. Propensity score matching was performed using R package MatchIt v4.5.1. Results: Among the 1,618 patients identified, the most frequent events were pain, sepsis, and fever. 56% of patients were female with an overall median age of 64 (range = [20, 95]). Men were predicted to have 16% more visits than females. 45% had commercial insurance, 39% were on Medicare, and 15% were on Medicaid or charity care. 39% had two or more visits during the 4 years of the study, and among those patients, the most frequent cancer types were gastrointestinal (32%) and breast (22%). Self-reported latino patients constituted 4% of all patients but had the highest average number of events (median = 2.07, range = [1, 9]). Patients who reported more-than-one-race or Asian ancestry had the lowest median number of events (1.56 and 1.64, respectively). In the matched cohort analysis, five co-morbidities were statistically significant (p < 0.05): a previous history of coagulopathy/pulmonary emboli, myocardial infarction, cardiac arrhythmias, depression, and weight loss (concordance = 0.58). 46% of all patients with an event had at least one of these 5 comorbidities. Conclusions: Demographic factors and specific comorbid conditions were associated with risk for requiring acute care intervention for chemotherapy toxicities. Future interventions will include introduction of risk-reducing monitoring in the outpatient setting for higher risk patients identified in this investigation to reduce the need for ED visits and inpatient hospitalizations.